Defensive mutualists affect outcross pollen transfer and male fitness in their host plant

Ant guards can increase plant fitness by deterring herbivores, but they may also reduce it by interfering with pollination. While ant impacts on herbivory have been well-studied, much less is known about their impacts on pollinators and associated consequences for plant pollination, particularly pollen transfer dynamics and outcrossing/selfing rates. We used field experiments to quantify the effect of ant guards on pollinator community composition, frequency and duration of flower visits, and cascading effects on outcrossing pollen transfer and pollen exports in Turnera velutina (Passifloraceae). Although ant patrolling did not affect pollinator community composition or visitation frequency, it decreased flower visit duration and the time pollinators spent foraging inside flowers. Such behavioural changes resulted in reduced pollen deposition on stigmas, decreased pollen exports (a proxy for male fitness) and significantly doubled outcross pollen transfer. This study contributes to our ...

护蚁（ant guards）可通过驱避植食者提升植物适合度，但也可能通过干扰传粉过程降低植物适合度。尽管学界已对蚂蚁对植食作用的影响开展了充分研究，但针对其影响传粉者及由此引发的植物传粉相关后果——尤其是花粉传递动态、异交/自交率——的认知仍较为匮乏。本研究以绒叶时钟花（Turnera velutina，西番莲科Passifloraceae）为研究材料，通过野外实验量化了护蚁对传粉者群落组成、访花频率与访花时长的影响，及其对异交花粉传递与花粉输出的级联效应。结果显示，蚂蚁巡逻行为未对传粉者群落组成及访花频率产生显著影响，但缩短了访花总时长以及传粉者在花内的觅食时长。此类行为变化导致柱头花粉沉积量降低、花粉输出量（雄性适合度的替代指标）下降，同时使异交花粉传递量显著提升一倍。本研究为我们对相关领域的研究作出了贡献。